The present invention relates to a cooling apparatus for removing the heat generated in electronic devices such as semiconductor elements or integrated circuit chips.
In a large-sized electronic computer system, it is demanded that the processing operation is performed at high speed. To this end, a circuit chip on which a large number of semiconductor elements are integrated has been developed in recent years. Further, in order to shortened the electronic wiring for interconnecting such integrated circuit chips, a method of mounting a large number of such integrated circuit chips in a micropackage has developed.
Various types of cooling apparatus of electronic devices especially for use in the large-sized electronic computer system have been proposed. Cooling apparatus of semiconductor chips each of which performs a highly effective cooling and has a flexible structure for absorbing errors in assembling component parts and thermal deformations in vertical and lateral directions are disclosed in Japanese Patent Unexamined Publications Nos. 60-126853, 63-204633, and 61-231744, U.S. Pat. No. 4,498,530, and the like.
In, for example, Japanese Patent Unexamined Publication No. 60-126853 where a coiled spring is used for pressing a thermal conductive member provided with fins onto each semiconductor chip, with bores for inserting the spring being formed in a housing and a central portion of the thermal conductive member so as to fix the spring. These bores for inserting the spring interfere with thermal diffusion of the heat from a base portion of the thermal conductive member to fins of the thermal conductive member and from fins fitted with the fins of the thermal conductive member to the housing, thus deteriorating the performance of heat conduction. When machining of the bores for fixing the coiled spring is carried out by a commonly used tool, a bore for inserting the spring needs to be formed in the fins on one side, and then, bores for fixing the spring need to be formed in both the housing and the thermal conductive member, thereby increasing the number of machining operations. Moreover, if the thermal conductive member, the housing and the fins are made of ceramic material, the machining cannot be done easily without taking a long period of time, which results in a technical problem concerning mass production efficiency and the like. Furthermore, even if the spring is designed to be supported in the fixing bores, the spring may fall down when the housing and the thermal conductive member are assembled because the outer diameter of the spring is less than the width of each groove between the fins, thus making it difficult to assemble the housing and the thermal conductive member.
The conventional cooling apparatus disclosed in Japanese Patent Unexamined Publications Nos. 63-204633 and 61-231744 also involve the same type of problems.
In the conventional cooling apparatus disclosed in U.S. Pat. No. 4,498,530, a leaf spring is used for pressing a thermal conductive member onto each electronic device, and therefore, it is necessary to provide special means for retaining the leaf spring, thereby complicating the structure of the apparatus.
Other than the above-described conventional examples, there is proposed a cooling apparatus where continuous coil-like fins are fitted to each other without clearances provided therebetween, as disclosed in U.S. Pat. No. 4,448,240. However, machining and assembling of this cooling apparatus cannot be done without difficulty, involving a problem that electronic devices are not allowed to be tilted.